From the Guidelines
Kaposi sarcoma is primarily caused by infection with human herpesvirus 8 (HHV-8), also known as Kaposi sarcoma-associated herpesvirus (KSHV), as evidenced by serologic confirmation of HHV-8 infection in 95%–98% of patients with Kaposi sarcoma 1. The development of Kaposi sarcoma is multifactorial, but immunosuppression plays a crucial role, with HIV/AIDS being the most common cause of immunosuppression leading to Kaposi sarcoma. Other causes of immunosuppression that can lead to Kaposi sarcoma include:
- Organ transplantation requiring immunosuppressive medications, resulting in iatrogenic or transplant-associated Kaposi sarcoma 1
- Advanced age causing natural immune decline
- Certain genetic factors that may predispose individuals to developing the disease The risk of Kaposi sarcoma development is correlated with CD4+ T-cell counts and HIV viral load, and effective antiretroviral therapy (ART) likely lowers the risk of Kaposi sarcoma development and improves prognosis for Kaposi sarcoma 1. Key factors that contribute to the development of Kaposi sarcoma include:
- HHV-8 infection
- Immunocompromised state
- Advanced age
- Genetic predisposition
- Other causes of immunosuppression The most critical factor in the development of Kaposi sarcoma is the presence of HHV-8 infection, which is universally associated with the disease 1.
From the Research
Causes of Kaposi Sarcoma
- Kaposi's sarcoma (KS) is a multifocal neoplasm of lymphatic endothelium-derived cells infected with human herpesvirus 8 (HHV-8) 2, 3, 4, 5.
- The disease is multifocal, with a course ranging from indolent, with only skin manifestations to fulminant, with extensive visceral involvement 5.
- HHV-8 infection can be considered a necessary but not sufficient condition for the development of KS, because further factors (genetic, immunologic, and environmental) are required 5.
- The role of cofactors can be attributed to their ability to interact with HHV-8, to affect the immune system, or to act as vasoactive agents 5.
Types of Kaposi Sarcoma
- Four clinical subtypes are distinguished: the classic, the endemic, the epidemic subtype in HIV positive patients and the iatrogenic subtype 2.
- KS also presents in individuals without HIV infection in older men (classic KS), in sub-Saharan Africa (endemic KS) and in transplant recipients (iatrogenic KS) 4.
- The aetiologic agent of KS is KS herpesvirus (KSHV; also known as human herpesvirus-8), and viral proteins can induce KS-associated cellular changes that enable the virus to evade the host immune system and allow the infected cell to survive and proliferate despite viral infection 4.
Risk Factors
- Immune dysfunction is a key factor in the development of KS 5.
- Genetic, immunologic, and environmental factors can contribute to the development of KS 5.
- The use of certain drugs, such as quinine analogues and angiotensin-converting enzyme inhibitors, has been linked to the onset of KS, although the role of these drugs is still controversial 5.